Saturday's south Wales derby is more than about just bragging rights as a possible £40m ticket to the glitzy Premier League ball could be the ultimate prize.

The 58th meeting between Cardiff City and Swansea City has been dubbed the richest and arguably biggest all-Wales showdown - for the record, the fixture dates back to a Ninian Park stalemate in October 1929.

An invite to the Championship play-off party - and a shot at the promised land of Premier League - is so close but yet so far away for the best of enemies this side of the Severn Bridge.

Both Bluebirds and Swans have been roosting in the play-off places for most of the season and failure now, with the finish line in sight, would be a fate worse than derby day defeat.

Rival bosses Dave Jones and Paulo Sousa have huge mutual respect

Saturday evening's showdown signals the start of the closing straight for both sides and with five games each remaining after their Easter extravaganza, slipping up against your biggest rivals could have a potentially catastrophic effect on their play-off hopes.

"Promotion to the Premier League would change each club's finances dramatically," said sports finance expert Professor Tom Cannon, from the University of Liverpool Management School.

"So, bearing in mind each club's position in the Championship table and the proximity to the end of the season, this is potentially the most lucrative South Wales derby in history.

"Promotion to the Premier League would add between £30m and £40m to a club's revenue stream."

History is littered with past South Wales derbies that have played pivotal roles in the league destiny of their neighbours.

Ron Healey's last-minute penalty save - earning a point as Swansea were promoted to the old Division One at the end of the 1980/81 season - helped Cardiff survive relegation to the old Division Three on goal difference.

Then there was the day in April 1965 when two of Swansea's most famous footballing sons, Ivor Allchurch and John Charles, relegated their home-town club as they scored two and three goals respectively for Cardiff in a five-goal rout in the old Division Two.

But in this 21st Century age of TV money, corporate cash, sponsorship and global branding, football finances are a different ball game.

"The top team in the Championship will earn between £7m to £8m in TV revenue," Cannon explained to BBC Sport.

Whichever Welsh team can win promotion to the Premier League, given its global reach as the world's most popular football league, would have a unique position globally

Professor Tom Cannon

"However, the bottom team in the Premier League would get £30m a season in TV revenue.

"And, even if the club is relegated after its first season, there is a parachute payment of around £15m for two seasons.

"On top of that you have added gate income because there is a world of difference between the gate receipts you'll get if Swansea, for example, were playing Manchester United compared to playing Barnsley as the club could charge premium prices as they would be certain of a full house.

"Another effect is sponsorship and merchandise income as sponsors are more likely to pay top dollar if Cardiff, for example, were playing Chelsea, Arsenal or United rather than the likes of Peterborough, Watford or Barnsley.

"That is no disrespect to those clubs but they just don't have the global media reach that sponsors demand."

Cardiff and Swansea lie side-by-side in the league table - separated by just three points - but their journey to fourth and fifth in the Championship is a complete contrast.

Dave Jones' Bluebirds are the powerful alley cats of the Championship whose free-scoring cutting edge has fired them to within sight of their dream.

Paulo Sousa's Swans, on the other hand, embody the way in which their manager played - the iron fist in a velvet glove approach - with distinction for European heavyweights Inter Milan, Juventus and Portugal.

And should Swansea qualify for the play-offs scoring at their current goal average, the lads from the Liberty would become the lowest scorers to reach the second-tier's top six since the play-off system was introduced in 1987.

Tate and Trundle's Swans bid to seal the first South Wales derby double

The contrasts continue off the field as debt-ridden Cardiff have been warned by the High Court they face extinction on 5 May if the club cannot pay a £1.9m tax bill.

And Cardiff's estimated £1m a month wage bill is double that of debt-free Swansea's, who know only too well the dangers of paying beyond their means having entered into a Company Voluntary Arrangement to survive in 2002.

"Swansea have developed a reputation for being a frugal, well-managed club," Cannon continued.

"Their past has made them more cautious and the club seem to be ahead of the game as, if you look at the Premier League, most indications suggest - certainly outside the top six - clubs are now wary of big payments and wages.

"By contrast, Cardiff, whose problems have been heavily publicised, are looking for new investment and have bordered on very serious financial difficulties this season."

Cannon believes the first side to reach the top flight will gather extra support from fans throughout the world.

"Both have very similar ambitions," he added. "In the case of Cardiff they are currently probably the only capital in Europe not to have a club in the top-flight of its league.

"Yet, whichever Welsh team can win promotion to the Premier League, given its global reach as the world's most popular football league, would have a unique position globally.

"A Welsh club in the Premier League would suddenly enjoy a global fan-base of Welsh people living in the United States, Australia, China, etc.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.